Requirements

If you don't use HTML5, adding "data" attributes to your HTML4 or XHTML pages might make them fail W3C markup validation. However, this shouldn't create any issues for web browsers or other user agents.

Installation

For automated installation in Rails, use the "jquery-rails" gem. Place this in your Gemfile:

gem'jquery-rails', '>= 1.0.12'

And run:

$ bundle install

This next step depends on your version of Rails.

a. For Rails 3.1, add these lines to the top of your app/assets/javascripts/application.js file:

//= require jquery//= require jquery_ujs

b. For Rails 3.0, run this command (add --ui if you want jQuery UI):

Be sure to get rid of the rails.js file if it exists, and instead use
the new jquery_ujs.js file that gets copied to the public directory.
Choose to overwrite jquery_ujs.js if prompted.

Now the template helper javascript_include_tag :defaults will generate SCRIPT tags to load jQuery and rails.js.

For Rails 2, you will need to manually implement the csrf_meta_tag helper and include it inside the <head> of your application layout.

The csrf_meta_tags (Rails 3.1) and csrf_meta_tag (Rails 3.0) helpers generate two meta tags containing values necessary for the cross-site request forgery protection built into Rails. Here is how to implement that helper in Rails 2: